Independent and Combined Association ofMuscleStrengthandCardiorespiratory Fitness in YouthWith Insulin Resistance and b-Cell Function in Young Adulthood The European Youth Heart Study

OBJECTIVEdTo examine the independent and combined association of isometric muscle strength of the abdomen and back and cardiorespiratory fitness (CRF) in youth with indices of glucose metabolism in young adulthood among boys and girls from the European Youth Heart Study. RESEARCH DESIGN AND METHODSdWe used data from a population-based pro-spective cohort study among youth followed-up for up to 12 years (n = 317). In youth, maximal voluntary contractions during isometric back extension and abdominal flexion were determined using a strain-gauge dynamometer and CRF was obtained from a maximal cycle ergometer test. Insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR]) and b-cell function (homeostasis model assessment of b-cell function [HOMA-B]) were estimated from fasting serum insulin and glucose that were obtained in youth and at follow-up in young adult-hood. RESULTSdFor each 1-SD difference in isometric muscle strength (0.16 N/kg) in youth, fast-ing insulin, HOMA-IR, and HOMA-B in young adulthood changed with 211.3 % (95 % CI, 217.0 to 25.2), 212.2 % (218.2 to 25.7), and 28.9 % (214.4 to 23.0), respectively, i